読んだら

if/when read

→ 読む
読ん read + Past tense + Conditional
verb · conditional Rare #40,937
if/when read
JA: この本を読んだら、感想を教えてください。
EN: When you finish reading this book, please tell me what you think.
Conjugation of 読む

どっちの本を先に読んだらいいと思う

Which book do you think I should read first?

その本読んだら私に返して

Once you’ve read that book, give it back to me.

読んだら燃やしてしまう

Once I've read it, I'll burn it.

— 暗殺の森 (1971)